#include <stdio.h>
unsigned long int fact(int n);
void main(){
	unsigned long int n;
	scanf("%u", &n);
	printf("%lu", fact(n));
	
}
unsigned long int fact(int n){
	unsigned long int i=1,ret=1;
	for (i=1;i<=n;i++){
		ret*=i;
	}
	return ret;
}
